Cisco Systems 7401ASR manual Boot Environment Variables

Appendix C Using the CompactFlash Disk

Boot Environment Variables

Boot Environment Variables

The contents of the boot environment variables, which are stored in the configuration file in NVRAM, determine the actions your system takes on bootup. To see the current settings of these variables, use the show bootvar command as follows:

Router> show bootvar

BOOT variable =

CONFIG_FILE variable =

Current CONFIG_FILE variable =

BOOTLDR variable does not exist

Configuration register is 0x100

Following are explanations for each of these boot environment variables:

•BOOT variable—Points to the Cisco IOS software image that you want to boot; you set it in configuration mode. The default software image is the CISCOxxx image (where xxx is a filename assigned by the system, if you do not enter a specific filename). The system then looks for the first image on the CompactFlash Disk in slot 0.

Enter configuration mode and specify a filename and CompactFlash Disk slot from which to boot using the configure terminal and boot system commands as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CTRL-Z.

System(config)# boot system flash disk0:rsp-p-mz.12-0

The result of this configuration file entry is that the BOOT variable is disk0: c7400-js-m...bin

CONFIG_FILE (configuration file) variable—Determines where the configuration is read from on bootup; you set it in configuration mode as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CTRL-Z.

System(config)# boot config disk0:configfile

The result of this configuration file entry is that the CONFIG_FILE variable is disk0:configfile.

•BOOTLDR (boot loader) variable—Determines which image is used as the boot helper (boot image); you set it in configuration mode as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CTRL-Z.

System(config)# boot bootldr bootflash:c7401-boot-mz

The result of this configuration file entry is that the BOOTLDR variable is bootflash:c7401-boot-mz.

•Configuration register variable—Instructs the system where to look for a bootable Cisco IOS software image; you set it as a hexadecimal value in configuration mode as follows:

Router# configure terminal

Enter configuration commands, one per line. End with CTRL-Z.

System(config)# config-register 0x102

The result of this configuration file entry is that the configuration register is set to hexadecimal 0x102. Please seeChapter 3, “Starting and Configuring,” page 3-9, for more information about the configuration register.

Cisco 7401ASR Installation and Configuration Guide

C-4 OL-5419-01 B0